JP2008018248A - Spacer for insertion between two vertebrae - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spacer to be inserted between two vertebrae. <P>SOLUTION: The spacer has variable axial length and comprises a first member 2 having a hollow interior and a tubular wall and a second member 3 having a hollow interior and a tubular wall. The second member 3 is slidable within the first member 2 in an axial direction for adjusting the overall length. At least the first member 2 or the second member 3 has an access opening 6, 9 in its wall. The opening 6, 9 having a size adapted for inserting bone grafts through the opening 6, 9 into the interior. The spacer further has length adjustment structures 15, 19, 20 engageable with an expansion tool for telescoping the second member 3 relative to the first member 2 and a locking structures 10, 11, 12 for fixing the axial length. The access opening, the length adjustment structures, and the locking structures are arranged so as to be accessible from the same side of the spacer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a spacer for insertion between two vertebrae. In particular, the invention relates to a spacer having an adjustable axial length that can be filled with a bone graft after insertion between vertebrae.

US 6,200,348 US6,616,695 B1 US 5,290,312 US6,524,341 B2 US 6,176,881 B1

  Spacers having an adjustable axial length are known from US 6,200,348. The spacer includes a first sleeve mold member and a second member that is slidably guided within the first member to adjust the overall length of the spacer. The axial length is adjusted by a ratchet notch provided on the outer wall of the second member and an engaging member provided on the first member. The spacer has a plurality of openings in its wall that allow bone cement to be inserted and blood vessels to grow.

  Typically, the spacer is filled with bone cement by injection after insertion between the vertebrae, or filled with bone material, particularly a bone graft, through the open end of the tubular spacer before being implanted in the patient's body. The length of the known spacer can be adjusted after the spacer is inserted between the two vertebrae. In certain circumstances, it may be desirable to add bone material to or remove bone material from the interior of the spacer after adjusting the axial length of the spacer.

  US 6,616,695 B1 describes a spacer for insertion between two vertebrae whose axial length can be adjusted. The spacer includes a first tubular part having a threaded inner surface and a second tubular part having a threaded outer surface, the part being a screw-nut connection that allows adjustment of the axial length of the spacer. Form. The first tubular part has a plurality of circular openings in its wall. The second tubular part has a plurality of elongated openings in its wall. The length of the spacer can be adjusted by rotating these parts relatively. This requires more space for adjusting the length than the sliding movement. Furthermore, the vertebral bodies can be damaged by the toothed endplates of the spacers during rotational movement. The elongated opening serves for the insertion of a fixing screw. The opening in the wall is too small to insert a bone graft.

  US Pat. No. 5,290,312 has an adjustable axial length comprising a first hollow parallelepiped component and a second hollow parallelepiped component slidable in the first component. A prosthetic vertebra having a thickness is described. Each component has an abutting end surface for abutting the vertebra and an anchoring window formed at the abutting end. In addition, each component has a first open side that establishes an access window and an open end formed opposite the abutting end. The spacer comprises means for preventing slidable movement between the components to establish the desired length. To connect the spacer with the vertebra, flexible bone cement is injected into the component through the access window and the flexible bone cement flows out of the fixation window and hardens. Since each component has an open side, bone grafts that would be inserted through this side can easily escape. Furthermore, the open side faces lead to reduced stability.

  US 6,524,341 B2 also discloses a spacer having an adjustable length. Rotational motion is required to expand and retract the spacer parts relative to each other.

  US 6,176,881 B1 discloses a spacer having an adjustable length. The spacer comprises an inner hollow body and an outer hollow body, the inner body having a stop mechanism on its outer surface, the outer body including an elastic element that can grip the stop mechanism, thereby being resistant to compression. Fix the spacer length so that there is. If it is desired for the hollow body to resist expansion, a locking screw located on one side of the spacer is used. If the length of the spacer is reduced again, the elastic element is moved using a tool acting on the opposite side of the spacer. A spacer similar to that disclosed in US Pat. No. 6,176,881 B1 is known under the trade name Synex. The spacer further has an access opening for introducing a bone graft. The object of the present invention is to provide a spacer for insertion between two vertebrae that can be adjusted in length, can be filled with bone cement as well as bone cement in situ, and has improved handling. That is.

  This object is solved by a spacer according to claim 1. Further developments are presented in the dependent claims.

  The spacer can be filled with a bone graft prior to insertion between the two vertebrae as usual. After inserting a spacer between the vertebrae and adjusting the axial length, additional bone grafts can be introduced through the access opening. Alternatively, all bone grafts can be inserted after inserting a spacer between vertebrae and adjusting the length.

  The spacer can be inflated by a sliding motion that requires less operating space and operating time compared to expansion by rotational motion.

  The access opening has a closed rim, which results in a higher mechanical stability of the spacer compared to an access window having an open side.

  The length adjusting element and the length fixing element are accessible from the same side of the spacer. This leads to improved handling. Furthermore, the access opening, length adjustment element and length fixing element are accessible from one side, which allows a MIS or MOS approach.

  The end section may be formed as a multiple cage structure. This results in a stronger fixation at the vertebra because the contact area is wider and the depth of penetration into the bone at the contact area is reduced, thus reducing damage to adjacent vertebrae. The outer cage profile of the multi-cage structure may be adapted to the vertebral body surface profile.

The spacer may be manufactured from a tube that is easier to manufacture than other shapes.
Further advantages of the present invention will become apparent from the description of embodiments in conjunction with the accompanying drawings.

  As can be seen in FIGS. 1 to 6, the spacer 1 according to one embodiment comprises a first cylindrical tubular member 2 and a second cylindrical tubular member 3. The outer diameter of the second tubular member 3 is selected to allow sliding guidance of the second tubular member 3 in the first tubular member 2.

The first tubular member 2 has a first end 4, an opposing second end 5, and a hollow interior surrounded by the wall of the tube. The wall at a predetermined distance from the first end 4 is provided with an access opening 6 extending over about half the length of the first tubular member 2. In the embodiment shown, the access opening is a rectangular opening. The length of the long side of the rectangle is about half of the length of the first tubular member 2, and the length of the short side is about one quarter of the length of the first tubular member 2. The dimensions of the access opening 6 are such that the natural bone graft can fill the opening during or after surgery and the natural bone graft can be removed from the opening.

  Similarly, the second tubular member has a first end 7, an opposing second end 8, and a hollow interior and wall defined by the tube. An access opening 9 is provided in the wall of the second tubular member at a distance from the second end. The access opening 9 extends over approximately half the length of the second tubular member 3. In the embodiment shown, the shape of the access opening 9 is a rectangle having the same dimensions as the access opening 6 of the first tubular member. In the assembled state as shown in FIG. 2, the second tubular member 3 is such that the first tubular member access opening 6 and the second tubular member access opening 9 are radially aligned. 1 is inserted into the tubular member 2.

  Each access opening of the tubular member is provided at a distance from the first end and the second end, respectively, so that the access opening is respectively a first end or a second by a portion of the wall. It is separated from the end and therefore has a closed rim.

  The position of the second tubular member 3 relative to the first tubular member 2 in the direction of the longitudinal axis L of the spacer can be fixed by a locking structure. The locking structure is formed by a plurality of threaded openings 10 that are axially aligned in the wall of the first tubular member 2. The threaded opening 10 is located on one side of the access opening 6 and close to the access opening so that the threaded opening is accessible by the surgeon during the operation from the same side as the access opening. Further, the locking structure includes a plurality of spherical fan-shaped recesses 11 arranged in a straight line in the direction of the longitudinal axis L of the spacer on the outer surface of the wall of the second tubular member 3. The recesses 11 are formed side by side and their depth is less than their radius. The straight recess 11 is one of the access openings 9 in the second tubular member 3 such that the straight threaded opening 10 coincides with the straight recess 11 in the assembled state as shown in FIGS. On the other side and near the access opening 9. The locking structure further comprises a locking screw 12 that can be screwed into the threaded opening 10. The locking screw 12 has a spherical fan-shaped convex portion 13 that fits into the spherical fan-shaped concave portion 11 on one side. On the opposite side, the locking screw 12 has a recess for engagement with the screwing tool. The straight recess 11 extends over at least the same length as the straight threaded opening 10. An unthreaded opening 10a can be provided in the straight threaded opening for engagement with a holding tool (not shown).

  As can be seen in FIGS. 2, 3 and 12, the first tubular member 2 extends from a distance from the first end 4 to a distance from the second end 5. An elongated opening 15 is provided. The length of the elongated opening 15 is approximately the same as the length of the access opening 6 so that the bone graft cannot penetrate the elongated opening 15, and the width of the elongated opening 15 is significantly smaller than the width of the access opening 6. Further, the first tubular member 2 includes a plurality of diamond-shaped openings 16 disposed in a region adjacent to the second end 5. The size of the diamond-shaped opening 16 is smaller than the size of the access opening 9 so that the bone graft cannot penetrate the diamond-shaped opening. The diamond-shaped openings 16 are arranged in rows in the circumferential direction, and one row is offset from an adjacent row in the axial direction by half the height of the diamond. The row of diamond-shaped openings 16 closest to the second end 5 is cut so that the openings open toward the second end 5 to form protrusions 17 for engagement with adjacent vertebrae. The

As can be seen in particular from FIGS. 1 and 4, the first tubular member 2 further comprises a plurality of circular openings 18 in the region starting at the first end 4. The circular opening 18 has a size that prevents the bone graft from being introduced and removed. The diamond-shaped opening 16 and the circular opening 18 help to allow blood vessels and tissue to grow.

  Similarly, the second tubular member 3 comprises a plurality of circular openings 19 adjacent to its second end 8 and a plurality of diamond-type openings adjacent to the first end 7. The circular opening 19 and the diamond-shaped opening 20 are sized so that no bone graft can be introduced or removed through these openings. Similar to the first tubular member 2, the row of diamond-shaped openings 20 closest to the first end 7 of the second tubular member is cut to form a protrusion 21 for engagement with the vertebral body. Is done.

  As can be seen in FIGS. 1 and 4, for example, a pin that can be fixed to the first tubular member 2 and can be guided in an elongated slit 28 (FIG. 4) provided in the second tubular member 3. 25 is provided to form a stop for preventing rotation and preventing separation of the first and second tubular members.

  The spacer further comprises a third tubular member 22 whose axial length is approximately the axial length of the region of the second tubular member in which the diamond-shaped opening 20 is located. The third tubular member 22 further comprises a diamond-shaped opening 23 in its wall and a protrusion 24 on both free ends. The third tubular member 22 is fixedly connected to the second tubular member by a pin 26 shown in the exploded schematic view in FIGS. 7 and 8 or by using screws, rivets or the like. The third tubular member 22 may have an elliptical cross section as shown in FIG. 7, or may have a circular cross section as shown in FIG. The end sections of the third tubular member and the second tubular member form a double cage structure, which improves the contact area with the vertebra compared to the contact area of the second tubular member only. Since the outer diameter of the second tubular member is smaller than the outer diameter of the first tubular member, the third tubular member is engaged with the vertebral body to enlarge the contact area and the shape of the ring of protrusions. Can be used to adapt to the contour of the end face.

  As can be seen in FIGS. 1 to 6, a fourth tubular member 27 similar to the third tubular member 22 is provided inside the first tubular member 2 at the free second end 5, Attached to the first tubular member 2 forms a double cage structure. The fourth tubular member 27 also includes a diamond-shaped opening and a protrusion for attachment to the bone.

  When assembled, the elongated opening 15 covers at least one of the circular opening 19 or the diamond-shaped opening 20 of the second tubular member 3. One of the elongated opening of the first tubular member and the circular or diamond shaped opening of the second tubular member allows the two tubular members to expand and compress relative to each other when engaged with the tool. An example of a length adjustment structure.

  In the illustrated embodiment, the access opening, locking structure, and length adjustment structure are disposed within a range of about one-half or less of the spacer circumference when assembled.

A length adjustment tool for nesting the second tubular member 3 relative to the first tubular member 2 is shown in FIGS. Tool 30 includes a tube 31 having a handle 32 at one end and a fork-shaped section 33 at the other end. The rotary shaft 34 bridges the fork section 33 at the free end. A heel-like structure 35 is pivotally connected to the fork section 33. The bag-like structure 35 can be pivoted about the axis 34. The heel-like structure 35 includes arms 35a and 35b that can be moved between a folded and unfolded position. One of the arms is constructed to engage the elongated opening 15 of the first tubular member 2 and the other arm is constructed to engage one of the circular or diamond shaped openings of the second tubular member 3. Is done.

  The tool further comprises a bar having a handle 37 at its free end. This bar is housed in the tube 31 and extends to the fork section 33. By rotating the rod with the handle 37, the bag-like structure 35 is moved so that the arms 35a and 35b open and close respectively.

  In use, the spacer is first filled with a bone graft before insertion between vertebrae. The length of the spacer is minimal. The spacer is then inserted between two adjacent vertebrae after removal of the vertebrae, for example to fill the space. The spacer length is then adjusted by nesting the second tubular member from the first tubular member. This movement is not a rotation but a sliding movement. The tool shown in FIGS. 12 and 13 is configured such that a scissor-like structure is inserted into the elongated hole 15 in the first tubular member with one arm 35a and the hole 19 or 20 in the second tubular member with the other arm 35b. Used to engage one of the two. By rotating the rod, the heel-like structure is swiveled and the second tubular member is nested from the first tubular member. When the desired length is achieved, the locking screw 12 is inserted into the threaded opening 10 until the spherical fan-shaped protrusion engages one of the spherical fan-shaped recesses 18. Since the access openings of the first tubular member and the second tubular member are aligned with each other, the spacer still has an opening large enough to insert a bone graft. A further bone graft is then inserted to completely fill the interior of the spacer.

  Since the locking structure and the elongated opening 15 that serve for expansion or compression are located on the same side, the spacer can be quickly adjusted to its desired axial length and can be fixed in this position. Because the access openings of the first and second tubular members are on the same side and near the locking structure, it can be quickly filled with a bone graft during surgery.

  The spacer may be coated to enhance blood vessel or tissue growth. The spacer may be coated with a different material on the outer and inner surfaces of the tubular member. The first and second tubular members can be coated with different materials.

  Modifications to the embodiment shown are possible. The shape of the access opening need not be rectangular. The access opening may have any shape that is large enough to allow a bone graft to be inserted. Two or more elongated openings 15 may be provided.

  Circular openings and diamond-shaped openings may be omitted or have other shapes if they are small enough that the bone graft cannot be removed or inserted. In this case, instead of the opening of the second tubular member for engagement with the tool, another surface structure may be provided on the second tubular member.

  The locking structure can also be modified. A spherical recess 11 can be provided in the inner wall of the first tubular member and a threaded opening can be provided in the wall of the second tubular member. The locking screw is then screwed into the opening threaded from the hollow interior.

  A tubular member having a circular cross section is shown. However, other cross-sectional shapes are possible. For example, the cross-sectional shape of the tubular member can be adapted to the contour of the end face of the vertebral body.

  The third tubular member and the fourth tubular member may also have a cross section that is different from a circular cross section or an elliptical cross section.

Additional tubular members can be attached to the end sections of the first and / or second tubular members to provide a multiple cage structure. Alternatively, the third and fourth tubular members can be omitted.

It is a disassembled perspective view of the Example of a spacer. FIG. 6 is a side perspective view of the assembled spacer with an axial length close to the minimum possible length. FIG. 3 is a side perspective view of the assembled extended spacer having a length longer than that shown in FIG. 2. FIG. 3 is a side view of the spacer of FIG. 2. FIG. 3 is a top view of the spacer of FIG. 2. FIG. 3 is a bottom view of the spacer of FIG. 2. FIG. 3 is an exploded schematic view of an end section of a spacer according to a first example viewed from above. FIG. 6 is an exploded schematic view of an end section of a spacer according to a second example viewed from above. FIG. 6 is a perspective view of a locking element. FIG. 11 is a side view of the locking element of FIG. 10. It is sectional drawing of the locking structure for fixing the axial direction length of a spacer. FIG. 6 is a side perspective view of a spacer engaged with a length adjustment tool. It is a perspective view of a length adjustment tool.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Spacer 2 1st member 3 2nd member 6,9 Access opening 10,11,12 Locking structure 15,19,20 Length adjustment structure

Claims (12)

A spacer for insertion between two vertebrae, said spacer having a variable axial length;
A first member (2) having a hollow interior and a tubular wall;
A second member (3) having a hollow interior and a tubular wall, the second member being slidable axially within the first member to adjust the overall length;
At least the first member (2) or the second member (3) is provided with an access opening (6, 9) in its wall, the size of the opening (6, 9) inserting a bone graft into the interior through the opening Is adapted for
The length adjustment structure (15, 19, 20) is engageable with a tool (30) for nesting the second member (3) relative to the first member (2);
A locking structure (10, 11, 12) for fixing the axial length is provided,
A spacer, wherein the access opening, the length adjustment structure and the locking structure are arranged to be accessible from the same side of the spacer.   The spacer of claim 1, wherein each of the first member (2) and the second member (3) comprises an access opening.   The spacer according to claim 2, wherein the opening (6) of the first member and the opening (9) of the second member at least partially overlap each other.   The spacer according to any one of claims 1 to 3, wherein the opening (6, 9) is sized so that a bone graft can be introduced in vivo.   Spacer according to any of the preceding claims, wherein the opening (6, 9) has a closed rim.   The locking structure (10, 11, 12) is for engaging a plurality of indentations (11) axially aligned with the wall of the first or second member and at least one of the indentations, respectively. The spacer in any one of Claim 1 to 5 provided with the engaging member (12) provided in another member.   The recess (11) is arranged on the outer surface of the second member (3), and the engaging member (12) comprises a protrusion (13) protruding from the inner surface of the first member (2). Spacers.   The length adjustment structure comprises an elongated opening (15) extending axially in the wall of the first member (2), and a structure for engagement with a tool in the wall of the second member (3) ( The spacer according to claim 1, comprising 19, 20).   The spacer of claim 8, wherein the structure (19, 20) comprises a hole overlapping the elongated opening.   10. At least the first or second member comprises a plurality of second openings (16, 18, 19, 20) in the wall that are smaller than the access opening so that a bone graft cannot be introduced. The spacer according to crab.   At least the first or second member comprises a first ring projection (17, 24) at its free end and at least a second ring projection (21) within the first ring projection for fixation to the vertebral body. The spacer according to claim 1, comprising: A spacer for insertion between two vertebrae, said spacer having a variable axial length;
A first member (2) having a hollow interior and a tubular wall;
A second member (3) having a hollow interior and a tubular wall, the second member being slidable axially within the first member to adjust the overall length;
At least the first or second member comprises a first ring projection (17, 24) at its free end and at least a second ring projection (21) within the first ring projection for fixation to the vertebral body. A spacer.

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